With the great success of tissue engineering over the past decade, there is a definite and urgent need to image the engineered living tissues in a qualitative and quantitative manner. The overall goal of our research program is to develop an advanced in-vivo imaging technology; namely, combined ultrasound, photoacoustic and elasticity microscopy, capable of visualizing both the structural and functional properties of living tissue such as internal micro- and macro-architecture, surface topography, conformation, transformation, compliance, homogeneity, growth rate, biomechanics and even cell function within tissues. The underlying hypothesis of this project is that remote, non-invasive, high-frequency, high-resolution, in-vivo microscopy is possible and will provide marked advantages over existing imaging tools available for tissue engineers. The fundamental premise of our research program is to develop an advanced in-vivo microscopy based on the fusion of three complementary imaging modalities - ultrasound, photoacoustics, and elastography - and to take full advantage of the many synergistic features of these systems, thus providing a much needed quantitative imaging tool to tissue engineers. Indeed, ultrasound-based imaging on the microscopic scale offers a conceptually and technically novel imaging tool for tissue engineering. The main objective of this application is to develop a prototype of the high-resolution, multifunctional microscope for tissue engineers. To achieve our objective, we will design and build the combined ultrasound- based microscopy system based on a mechanically scanned, single element transducer interfaced with a laser source. We will also develop algorithms for ultrasound, photoacoustic and elasticity imaging to optimize the performance of the combined system. We will then test the developed microscope and corresponding signal and image processing algorithms using tissue mimicking phantoms. Finally, based on the insights gathered during the project, we will outline the design and technical specifications of an in-vivo microscopy system. The long-range goal of our research program is to develop a combined ultrasound-based microscopy system for tissue engineers. [unreadable] [unreadable] [unreadable]